Heat oven to 110°C (230 °F).

Line 2 baking sheets with parchment paper.

Beat the egg whites until foamy. Gradually add the sugar, mixing well after each addition. Keep beating until stiff glossy peaks form.

Using a rubber spatula or wooden spoon carefully fold in ground walnuts until combined. Ultimately gently fold in ground cookies and mix until incorporated.

Place the chopped walnuts in a shallow dish. Take a small portion of mixture (size of a walnut) using a spoon, pop it into the dish, toss with some more chopped walnuts and shape the balls into crescents.

Place the crescents onto a parchment-lined baking sheet.

Bake/dry on the middle rack for around 30 minutes.

Baked like this, the meringue cookies would be crisp on the outside, remaining soft inside. If you prefer your cookies completely dried and crunchy, bake them for 10-15 minutes longer.

Once baked, leave the crescents to cool for several minutes before transferring them to the wire rack.